Spatial–temporal variations of oceanographic parameters in the Zhoushan sea area of the East China Sea based on remote sensing datasets

The study of the variation and development trend of regional oceanographic parameters is of great significance to the prevention and mitigation of disasters, the development and utilization of oceans, the guidance of human activities at sea, and the monitoring of the El Nino phenomenon. As an important fishery in China, the changes in oceanographic parameters have severely affected the development of the Zhoushan Islands. The spatial–temporal pattern evolution of oceanographic parameters and the response of oceanographic parameters and El Nino in the Zhoushan sea area are analyzed in this study. The remote sensing datasets of sea surface salinity (SSS), sea surface temperature (SST), sea surface height (SSH), and chlorophyll concentration (Chl) in the Zhoushan sea area were collected and averaged spatially, temporally, and yearly, in order to analyze the variability monthly and yearly, and during El Nino. The results are as follows: (1) SSS is smallest near the shore and increases with distance offshore; SST has obvious seasonal variation; the maximum variation of SSH occurred in the coastal area; and a high-value zone of Chl arises during spring and summer. (2) In the recent twenty years, SSS increased at a rate of 0.1241 PSU per year. SST, SSH, and Chl decrease at 0.0294 °C per year, 0.14 cm per year, and 0.0853 mg/m3 per year, respectively. (3) Different types of El Ninos have different effects on oceanographic parameters.